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A/C Pressure Zone "D" Diagnosis

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.
NOTE: Tools Required: ACR 2000 Air Conditioning Service Center (J-43600) or equivalent.
  1. Were you sent here from the A/C performance test? If so, go to next step. If not, go to A/C SYSTEM PERFORMANCE  under PERFORMANCE TESTS.
  2. Feel the liquid line before the orifice tube. Is the liquid line cold before the orifice tube? If so, go to next step. If not, go to step  8.
    3. NOTE: The high side components should feel warm/hot from the compressor all the way to the orifice tube.
  3. Feel along the surfaces of the following high side components for a sudden drop in temperature:
    • The compressor Discharge Hose.
    • The Condenser.
    • The liquid line between the Condenser and the Orifice Tube.
    Is there an abrupt drop in temperature noted along the surfaces of any of the listed components? If so, go to step  7. If not, go to next step.
  4. Feel the liquid line at the orifice tube location for extreme cold, possibly accompanied by heavy frost. Feel along the liquid line after the orifice tube location for warm temperature. Is the liquid line extremely cold at the orifice tube location and warm after the orifice tube location? If so, go to step  11. If not, go to next step.
  5. Feel along the surfaces of the following low side components for a sudden change in temperature:
    • The Evaporator Inlet Tube between the Orifice Tube and the Evaporator Core.
    • The Evaporator Outlet Tube between the Evaporator Core and the Compressor.
    • The Accumulator.
    • The Compressor Suction Hose.
    Is there an abrupt temperature change felt along the surfaces of any of the listed components? If so, go to step  7. If not, go to next step.
  6. Feel along the surfaces of low and high side components to compare the overall temperatures:
    • The evaporator inlet tube between the orifice tube and the evaporator core.
    • The evaporator outlet tube and the compressor.
    • The compressor suction hose.
    • The compressor discharge hose.
    • The condenser.
    • The evaporator inlet tube between the condenser and the orifice tube.
    Are the overall temperatures of the low and high side components close to the same (both only mildly warm)? If so, go to step  14. If not go to step  8.
  7. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Remove the restriction from the component, or replace the component which produced an abrupt temperature drop. After repairs are completed, go to step  9.
  8. Recover the refrigerant and evacuate the system. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Record the weight of the recovered refrigerant. Is the weight of the recovered refrigerant charge equal to or above 1.65 lbs (0.75 kg)? If so, go to next step. If not, go to next step.
  9. Recharge the A/C system. Is the cooling performance improved? If so, go to step  21. If not, go to next step.
  10. Leak test the system. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Repair any leaks. After repairs are completed, go to step  21.
  11. The orifice tube is restricted or damaged. Replace the orifice tube. See ORIFICE SOLENOID & SCREEN . If the orifice tube was restricted, note the type of debris present. Are there metal flakes present? If so go to next step. If not, go to step  13.
  12. Remove the compressor hose assembly from the vehicle. Inspect the hose for debris by blowing shop air through one end of the hose while covering the other end with a shop towel. Note the amount of debris collected in the shop towel. Is there a large amount of debris collected in the shop towel? If so, go to step  18. If not, go to step  20.
  13. If the orifice tube was restricted with a Brown/Black residue, flush the A/C system. See FLUSHING PROCEDURES in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Replace the accumulator. See ACCUMULATOR  under REMOVAL & INSTALLATION. After repairs are completed, go to step  21.
  14. Recover the refrigerant. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Disconnect the Compressor Hose from the Compressor. See COMPRESSOR HOSE  under REMOVAL & INSTALLATION. Inspect for the presence of debris in the Compressor suction port. Is there debris present in the Compressor suction port? If so, go to next step. If not, go to step  19.
  15. Remove the debris from the suction port. Inspect the orifice tube for damage or debris. Is there evidence of damage or debris? If so, go to step  17. If not, go to next step.
  16. If the orifice tube does not show any signs of damage or debris: Remove the Compressor Hose assembly from the vehicle. Inspect the hose for debris by blowing shop air through one end of the hose while covering the other end with a shop towel. Note the amount of debris collected in the shop towel. Is there a large amount of debris collected in the shop towel? If so, go to step  18. If not, go to step  19.
  17. Replace the orifice tube. See ORIFICE SOLENOID & SCREEN  under REMOVAL & INSTALLATION. If the orifice tube was restricted, note the type of debris present. Are there metal flakes present? If so, go to step  12. If not, go to step  13.
  18. If there was a large amount of debris collected in the shop towel from the compressor hose assembly:
    • Replace the accumulator. See ACCUMULATOR  under REMOVAL & INSTALLATION.
    After repairs are completed, go to next step.
  19. Install the compressor hose assembly. See COMPRESSOR HOSE  under REMOVAL & INSTALLATION. After repairs are completed, go to step  21.
  20. Install the compressor hose assembly. See COMPRESSOR HOSE  under REMOVAL & INSTALLATION. Recharge the A/C system. After repairs are completed, go to step  21.
  21. Record the low and high side pressures and the I/P panel outlet air temperature after repairs are performed. Compare the pressures and outlet temperature to those listed in the A/C performance table. See A/C PERFORMANCE SPECIFICATIONS (3.5L V6 ENGINE)  or A/C PERFORMANCE SPECIFICATIONS (4.0L V8 ENGINE)  table. Are the readings within the specified ranges? If so, go to next step. If not, go to A/C SYSTEM PERFORMANCE  under PERFORMANCE TESTS.
  22. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
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